Flow Arrows on 3D Surface

TopoGX can display flow arrows, which point in the direction that water would flow if it were on the surface.
The steepest slopes are shown with red arrows, and the flatest slopes with black.

On this example, where a roundabout has been surveyed, we can see that the surveyor has done a very good job,
because the flow arrows confirm the correct road slopes for an engineer designed roundabout.

Flow arrows are very useful for appraising a piece of land.
For example, if you are a developer evaluating the potential for building houses on a site.